Process of making coke and combustible gas



July 31, 1934- w. w. 0051.1.

EROCES'S OF. MAKING COKE AND COMBUSTIBLE GAS Filed Nov. 1950 iHydrocarbon 7, w ll/10411111111 OMMWaM' j l nveni'or Patented July a.rats t a g gg g iii an ait raocass or no, (coma cormnsrnsaa ens Wiliiam@deil, @hicago, m. Application November ll, 1030, Serial No. 492,870

c claims. (or. 202--23) My process relates to the method of increasingto that of the coke oven gas. This invention the gas making capacity ofa coal carbonizing unit diflers from the" disclosure in my patentreferred by causing reactions to occur between steam and to above inthat the operation is not performed in hydrocarbons prior to andsimultaneous with the cycles with a given fuel bed and there isno-initial cooling of the carbonized product which is usually airblasting to heat said fuel bed. In air blasting 69 coke. The reactionsare caused to occur in the a bed of ignitedcoke, as in a water gasgenerator, presence of incandescent carbonaceous material. thetemperature zone immediately after the blast The objects of thisinvention are: is a gradient, the highest temperature being at 1. Toincrease the gas making capacity of a coal the bottom and the lowesttemperature at the top. 1 carbonizing unit, such as vertical retorts.Therefore, in introducing steam and hydrocarbon 2. Produce low-densitygas having a high hyeither upwardly. or downwardly, the reactants drogencontent. contact solids at diflerent temperatures in the 3. Makepossible the more flexible use of a coal different zones, whereas inintroducing steam and carbonizing unit in generating manufactured gas.hydrocarbon into the base 'of a vertical retort 5 4. Cool the coke madesimultaneous with the when the charge is freshly carbonized the tem- 7generation of gas by reactions which yield a perature throughout themass in the retort is greater volume of gas per unit of available heatmore nearly uniform, allowing a more complete stored in the coke mass.conversion in the reactions of steam with said hy- 5. Use hydrocarbon'gases and hydrocarbon drocarbon and steam with the carbon of the in- 20mists in a supplementary method of making gas candescent coke. In otherwords, an excess of in coal carbonizers. steam may be used beyond thatrequired for The other objects will become apparent from chemicalreaction with the hydrocarbon without the disclosures made herein. -awaste of steam and without burning fuel, and

I have shown in my Patent No. 1,762,100, issued especially for bringingthe carbon to incandes- 25 June 3, 1930, that hydrocarbons react withsteam cence. I, therefore, attain in practicing this procin the presenceof heated solids, forming carbon ess a higher thermal efiiciency thancan be obmonoxide and hydrogen. In this instance I betained inalternately blasting an ignited fuel bed lieve I have an invention inwhich particularly with air and with mixed steam and a hydrocarhighefficiencies are obtained in the production of bon. This feature alone Ibelieve makes the reaction products. For example, considering the hereindescribed method of procedure patently carbonizing unit to comprisevertical retorts, it is novel over the disclosures of my patent referredcommon practice to steam the retorts after the to above. In theprocessdisclosed in that patent, carbonization is substantiallycomplete, that is, it is not economical to pass higher hydrocarbonssteam is introduced preferably in the base of the than methane ormixtures containing methane 5 mass of incandescent coke and passedupwardly and higher hydrocarbons into the fuel bed under therethrough.In passing through the hot coke conditions whereby only partialdecomposition or chemical reaction occurs whereby carbon monoxpartialreaction occurs; in the present case hyide and hydrogen are formed bythe well known drocarbons may be introduced into the retort water gasreaction which is'endothermic, and the along with steam even after thetemperature of 40 coke is simultaneously cooled. I find that bysubthe'coke mass has fallen to a point where only stituting a gaseoushydrocarbon or a very finely partial reaction occurs, and beneficialresults are atomized hydrocarbon for a portion of the steam, obtained.In this instance, the calorific value of t and particularly during theearly. stage of the the resulting gas is higher by virtue of themethsteaming operation, a larger yield of gas is obane or otherhydrocarbons that have been formed 45 tained than when steam is usedalone. The explain the retort or which passed through the retort nation'of this result is to be found in the fact that undecomposed. I find itis possible and economiless heat is required as heat of reaction in thecal to use highly'atomized mists of hydrocarbons formation of gas by thehydrocarbon reaction along with' steam as a medium for partly coolingwith steam than by the reaction of steam with the incandescent coke in acarbonizer simulta- 50 carbon. I find, further, that with straightsteamneously forming besides carbon monoxide and hying the resultantmixed gas has a higher specific drogen some hydrocarbon gas. Thus, notonly is gravity than the ordinary coke-oven gas from the volume of gasincreased per unit of coal coking coal, whereas when a. hydrocarbon isemcharged into the retort, but the calorific value .of

ployed along with steam as a cooling medium the the resultant mixed gasis higher than would re- 55 resultant mixed gas has a specific gravitynearer sult with straight steaming.

Another difference between this process and the patented processenumerated above is the effect of the difference in temperature. In thepatented process high temperatures are employed, namely: those suitablefor the substantially complete decomposition of methanejwhereas in thiscase the fuel bed is more uniformly heated but to a lower temperature.Under the conditions obtaining in the ordinary carbonization of coal inthe production of coke, as in a vertical retort, any deposited carbonresulting from the employment of a hydrocarbon mist is not in the formof a carbon black but rather in the form of coke; This result isprobably because of the lower temperature obtaining in the retort thanin the hot zone of a Water gas generator.

While I usually prefer to have the steam and hydrocarbon gas or thesteam and hydrocarbon mist thoroughly mixed before they are allowed tocontact with the incandescent coke in the carbonizer, it is notnecessary to thus introduce it. In some instances it is preferable tointroduce the hydrocarbon separately from the steam and when introducedfrom beneath the incandescent coke it is preferable to admit thehydrocarbons at a higher level than the steam. It is understood that thesteam and hydrocarbons may be introduced into the carbonized fueldownwardly from the top, upwardly from below or in any other suitablemanner; I prefer, however, to introduce them upwardly from beneath thecharge.

Because of the difference in the readiness with which varioushydrocarbons crack, it is possible by the selection of the hydrocarbonor hydrocarbons to obtain a varied efiect in thus making gas,

for example: when natural gas is passed through the fuel bed all of theethane and a portion of the methane reacts with steam during theforepart of this phase of gas making, whereas in a subsequent phase themethane is not appreciably reacted, only the ethane and higherhydrocarbons being re-formed. When natural gas or similar obtainedtherefrom such as methane, ethane,

propane, butane, pentane, higher parafiins, petroleum-refinery gas,light oil, atomized petroleum products and other hydrocarbons.

I find that the gas making capacity of a carbonizer adapted forcarbonizing solid fuel can be further increased by introducing into thecarbonizer during the carbonizing period a hydrocarbon gas or mist,preferably at a slow rate, whereby equalization of temperature in thecoking mass is approached and the hydrocarbon is only partly decomposed.The free carbon liberated by the thermal decomposition is absorbed bythe tar and does not appear in the outlet gas as a form of carbon black.It is of course recognized that when a large quantity of saidhydrocarbon is rapidly introduced into a small volume of coking coalheated to incandescence so large an amount of carbon black may beliberated that some of it will appear in the gas. The amount ofhydrocarbon I prefer to employ is that whereby substantially all of theliberated carbon is absorbed by the tar and the coking mass. y

The thermal decomposition of hydrocarbons is,

in most cases, endothermic, that is, heat is absorbed during reaction.This means that the use of certain amounts of hydrocarbon during thecoking period would tend to increase the coking time (time required forcarbonizing the coal or other solid fuel) by virtue of the heat absorbedby reaction. The amount of hydrocarbon used can be so regulated that itfunctions as a means of controlling the time of carbonizing (duration ofthe period of carbonization) in such a manner that the volume of gasproduced can be maintained simultaneous with a decrease in cokeproduction per unit of time (by virtue of an increase in the duration ofcoking period) and the quality of coke made is improved as a result ofgreater uniformity in the rate of heating of the coal in the variousparts of the coking mass. It is commonly desirable, on the part of cokeoven operators, to slow the rate of carbonization during certain periodsof the year when coke is not in great demand, without diminishing theoutput of gaseous heat energy or materially increasing the amount ofheat consumed in the process per therm of gas produced. The describedprocedure permits this efiect to be obtained.

When a maximum output of coke is desired it is preferable and in somecases essential to preheat the hydrocarbon used prior to introducing itinto the coking mass. This tends to neutralize the endothermic effect ofthe decomposition or 105 partial decomposition of the hydrocarbon.Certain efiects obtainable will become apparent from a scrutiny of thefollowing table:

Approximate heat of formation at constant pressure 1 10 Yield of hy-Heat of reacdrocarbon by tion per foot Heat oi com lniletely ofhydrggten nr mn crac mg evo ve y Hydrocarbon B.t.u. per volume ofcracking a cubic loot hydrocarbon hydrocarbon into its gas into itselements elements Volumes B. t. u. MethaneOH4 +103 2 51. 5 Ethane-0211a-+136 3 +45. 3 Propane-Oil +167 4 +41. 7 Butane-04H"; +202 5 +40. 4PentaneO H +228 6 +38. 0 Henna-00H +291 7 +41. 4 EthyleneCzH4. -13 2 6.5 Propylene-Cilia +15 3 +5. 0

ButyleneC4H +51 5 +10. 2 BeuzeneCsHa 47 3 -15. 7

Attention is called to the fact that benzene, a by-product of the coalcarbonizing industry, has a negative heat of reaction. This means thatthe only heat absorbed making gas om benzene is expressed in the heatcapacity of the resulting gas plus the heat of reaction which isnegative, making it possible with some superheating to generate gas fromthis material with substan- 1135 tially zero amount of absorption ofheat from the coking mass. Some steam, preferably superheated, mayadvantageously be used with the hydrocarbon. Ethylene behaves in amanner similar to benzene in the coking mass except that there is lesstendency for the formation of naphthalene. The relative heatrequirements are indicated by the table.

The rate of introducing the hydrocarbon into the coking mass or into theincandescent coke may vary. The rate preferred depends upon thetemperature in the solid fuel mass, the rate of 7 input of heat, theamount of superheating of said hydrocarbon, the output of coke desiredand the gasificatio'e- 'efiect desired. When steam is admitted'simultaneously with the hydrocarbon, it also is a factor influencing therate of introduction of the hydrocarbon. When the hydrocarbon is wellsuperheated it can efiectively be introduced at a faster rate than whennot superheated, other factors remaining the sanie. Likewise, to obtaina given cracking efiect the rate may be greater as the temperature ofthe coking mass rises. The greater the amount of steam used, the lessthe amount of hydrocarbonvused other things remaining the same; thisapplies chiefly when steam is used in excess of the amount rerequired tosatisfy the chemical reaction with the hydrocarbon- Examples of thelatter type of reaction, which are not carried to completion areNormally I prefer to usechiefiy the straight hydrocarbon during thecoking stage of carboni zation, but if steam is used simultaneously withit the relative amount of said steam used may be appreciably less thanindicated by the equations above, that is, less than the molecularrequirements in producing carbon monoxide and hydrogen, withoutproducing carbon black in the outlet gas. The reason for this istwofold, namely, because some of the hydrocarbon does not completely crackor react and because a portion is decomposed yielding carbon, hydrogenand Toydrocarbon, the liberated carbon being absorbed by the coking massand the tarry matter. This is an advantage gained, in this manner ofreforming, over other processes, so far as I am aware. Even when usingbituminous coal in a 'water gas generator in producing gas, the steamrequirements are greater than when the hydrocarbon is introduced into acoal carbonizer during the coking operation. My process is thus entirelydifierent from that revealed in the patent re-; ferred to above, No.1,762,100.

Although my process can be practiced in various types of coalcarbonizers, retorts and ovens now in common use as well as in a woodcharring apparatus, I prefer to show bygan illustration how the processmay be practiced. The accompanying figure is a diagrammatic sketch invertical cross section, of one type of oven or retort wherein my processmay be practiced; the connecting conduits are shown in elevation.

In the figure the retort has walls 1, with heating fiues 2, fuelcharging door 3, discharge hopper for the residue or by-product coke orchar, discharge door 5, discharge mechanism 6, ste'am supply lines 10and 16 with control valves 9 and 15, fuel supply line 11, for supplyingfuel to heat the retort, and gas off-take 13 with valve 14.

aces

valve 24 and inlet 13; up-run hydrocarbon gas is introduced throughvalve '7 and inlet 8.

In the operation of the process I may proceed as follows: Charge thesolid fuel to be carbonized into the retort through '3, close 3 andapply heat to the retort as, for example, by burning a gaseous fuel inthe heating flues 2 by admitting fuel gas through 11 and 12, drawing inair for its combustion through 22 and 23 or'by inspiration or othermeans. When a desired temperature is reached in the coking mass ahydrocarbon gas is introduced into 4 and into the coking mass through 8by opening valve 7; the hydrocarbon thus admitted passes upwardly intothe coking mass 17 and the reaction products are discharged with thegaseous products of carbonization through 13 and 14. The steam isadmitted through 10 by opening valve 9. Air is introduced through 19 byopening valve 18. The relative amounts of steam, air and hydrocarbonused are When the hydrocarbon, with or without air, steam or both, isadmitted to the retort from above the coking mass as through 24, thevalve 14 is closed and the gaseous products are df'scharged through 8,25 and 26. In this instance the inlet valves for air and steam are at 21and 15 respectively.

When it is desirable to discharge the coke it is accomplished by openingthe discharge door 5 and operating discharge device 6, rotating it.

It is understood that I do not limit myself to the use of the particularcarbonizer shown inthe figure in the practice of my invention; variousmodifications can readily be conceived in which a vaporized or gaseousfuel and steam, or an equivalent mixture, can be introduced into a bedof solid fuel dunng the process of its carbonizetion.

For the purpose of clearness I desire to describamy process, somewhatsummarily as fol-' lows:

(1) Introduce a hydrocarbon in a fine state of subdivision, beingpreferably a gas or fog, into the mass of solid fuel confined in,acarbonizer, during at least a portion of the carbonization period ordirectly thereafter.

(2) Introducing, when so desired, some steam simultaneous with saidhydrocarbon for the purposes of producing an additional cooling effect,causing greater dispersion of said hydrocarbon and causing the formationof a denser gas by virtue of the carbon monoxide and hydrocarbon gasformed. The latter gas (hydrocarbon gas) is formed as a result ofpyrolysis of the hydrocarbon introduced with the steam.

It is understood that the rate of introducing the hydrocarbon may beincreased during the steam line 16 with valve 15 is provided forprogress of carbon'ization, being as low as zero troducing steam fromabove the carbonizing fuel, and an air pipe for downwardly blasting withair is shown at 20 with valve 21. The down-run gas produced is removedthrough pipe connections 8 and 25 and valve 26. The solid fuel such ascoln'ng coal, 'lignite, petroleum refinery solid residuum. commonlycalled coke, sub-bituminous coal or other solid fuel that does notbecome liquid upon heating in process of carbonizing is shown at 17; theconnections for upwardly blasting with air include pipe 19 controlled byvalve 18. Air inlet and valve for the combustion of the fuel gas areshown respectively at 22 and 23. The down-run hydrocarbon is introducedthrough during an earlystage and be so high during .a subsequent stagethat the composite gas made in the carbonizer per unit of time, otherfactors remaining substantially the same, is materially increased. Analternative eirectis: the gas makingv capacity of the carbonizer ismaintained.

substantially normal but the production of coke per unit of timeismaterially reduced. I claim that by the use of my process eitherperiodically or continuously throughout the year in conjunction with acoal carbonizer one can operate with greater flexibility in the controlof output of coke, gas and by-products. It is understood that thehydrocarbon may be introduced without steam particularly when used inother stages than the last stage of carbonization. When using methane asthe hydrocarbon, or a gas largely comprised of methane, I prefer not tointroduce the hydrocarbon in' the earlystage of carbonization'unless itis preheated. Under this condition very little methane'is decomposed buta beneficial effect is obtained, namely, the middle of the mass of solidfuel is more readily and rapidly heated and the whole charge is moreuniformly heated than without the use of said hydrocarbon. The volume ofcondensable matter produced is greater not only by the amount ofhydrocarbon added but by the preservation of heavy hydrocarbons normallycracked in the process but which are not so completely cracked whenswept from the carbonizer more rapidly than in ordinary practice.

Ethylene, propylene and other hydrocarbons such as propane, butane, andpetroleum-refinery gas may be used and appreciably cracked attemperatures below that at which methane decomposes or reacts withsteam. Thus with hot petroleum-refinery gasor the equivalent, I preferto introduce it during a large portion of the carbonization period,increasing the rate of introduction as the temperature rises,introducing steam along with or simultaneously with it during the latestage'of carbonization, finally discontinuing the admission of therefinery gas and continuing with the steaming for a brief period for thepurpose of cleaning the coke or other product of carbonization.

I do not confine myself to the carbonization of coal in the practice ofmy process or to a particular type of carbonizer but the vertical retortor slot oven is referred to as being suitable for the purpose.

In my Patent No. 1,762,100 I claimed the process of making mixed gascomprising hydrogen and carbon monoxide by substantially completereaction between steam and a hydrocarbon whereas in this application Iclaim the process of making a mixed gas comprising hydrogen, carbonmonoxide and hydrocarbon gas. This process can be employed at lowertemperatures than the enumerated patented process and therefore Ibelieve that it should not be confused as a special case or specialapplication of the former but rather as a distinctly and patentablydifferent process.

I have stated that the hydrocarbon gas or the mist introduced into thesolid fuel in process of carbonizing is admitted at a slow rate; thisterm is also used in the claims and therefore its meaning should beclarified. I have found that when a hydrocarbon such as ethane, propane,

" butane, refinery gas and other hydrocarbons having a greater molecularweight than methane are introduced into a coking bed of coal, the amountof decomposition of said hydrocarbon increases with rise in temperature,the hydrocarbons of high molecular weight cracking more readily thanthose of low molecular weight. When the temperature in the fuel mass israther high, that is, above 1500 to 1800 Fahrenheit the percentageamount of decomposition is great. If the hydrocarbon is introduced toorapidly some carbon black passes through with the generated gas,particularly when no steam is used or when very little steam is used. Iprefer to so control the rate of introducing the hydrocarbon into thecoking or carbonizing mass that the amount of free carbon blackentrained in the generated gas is substantially zero. It is recognizedthat at relatively low temperatures the time of contact or time ofexposure to the hotmass is a factor in completing cracking and thereforethe percentage amount of cracking under low temperature conditions lesscracking occursper 1000 cubic feet of hydrocarbon passed at high ratesthan at slow rates but the amount of carbon carried out of thecarbonizer entrained in the gas is also a function of velocity.Therefore when conditions are such that there is a tendency for carbonto pass out entrained in the gas the tendency can be reduced tosubstantially zero by decreasing the rate of admission of thehydrocarbon, or, at high temperatures increasing the amount of steam, orby both. By free carbon black is meant the carbon particles resultingfrom cracking of the hydrocarbon that are not absorbed by the tarproduced during carbonization or deposited on the solid fuel. Methane,does not decompose appreciably at relatively low temperatures hencecarbon entrainment is not en- 'countered using it as the hydrocarbonunless used at elevated temperature.

I commonly prefer to adjust the rate of introduction of the hydrocarbonor hydrocarbon and steam so that a definite volume of gas is made perunit of time, or so that a definite amount of solid fuel is carbonizedper unit of time. By controlling the amount of preheating of thehydrocarbon and the rate of introduction of steam and hydrocarbon it ispossible to accomplish this result, For example, using the hydrocarbonat a given rate over an appreciable portion of the carbonization periodthe time required for completely carbonizing coal is longer than isnormal but the gas production is as great or greater than normalaccording to the amount of hydrocarbon used, whereas if the hydrocarbonis preheated the output of gas is increased and the coking time notappreciably decreased. The specific gravity of the gas made iscontrolled bycontrolling the relative amounts of hydrocarbon introducedduring the high and the low-temperature stages of carbonization. Gashaving the lower density is produced from the hydrocarbon used at a slowrate at high temperature, above about 1500 F. whereas at relatively lowtemperatures the specific gravity of the generated gas is higher.

Without preheating the hydrocarbon and using it (in this example naturalgas) during the last stage of carbonization only along with some steam,for cooling the coke, I find that I can increase the gas-making capacityof a vertical retort, carbonizing bituminous coal, from 10 to 20 percent without decreasing the carbonizing capacity of the retorts. Thetotal amount of natural gas required in this case is about 6 to 12 percent of the normal amount of gas made by straight carbonization, namelyabout 680 to 1320 cubic feet per ton of coal carbonized. When thenautral gas is preheated a greater gas-making capacity. can be obtainedwithout reducing coke output. By a more extended use of the natural gasor the gasing period the gas-making capacity of the retort is furtherincreased but the coke output decreased. The maximum capacity for cokeand gas is obtained when using preheated unsaturates with a minimumamount of steam, other factors remaining the same.

The calorific value of the generated gas is, in all cases, greater than300 B. t. u. per cubic foot. It may be that of average city gas, about550 B. t. u. per cubic foot or, higher or lower according to conditions,under control.

For example, 7

, carbonizer.

aaeaose the last period of carbonization, when the temperature is higherthan about 1800 Fahrenheit, and at so slow a rate that cracking isfairly well complete the generated gas resulting from cracking or fromthe steam hydrocarbon reaction, has

a caloroflc value of about 350 to 450 B. t. u per cubic foot andcomprises hydrogen, methane and carbon monoxide. As the temperaturefalls, or rather at low temperature or at somewhat faster rates theamount of methane in the generated gas increases and with it thecalorific value of said gas is'increased.

By using a liquid hydrocarbon, preheated and under superatmosphericpressure, releasing the claims is understood to include a gas or ahighly atomized liquid hydrocarbon.

It should be noted that the yield of motor fuel per ton of coalcarbonized is increased by the employment of hydrocarbons in the mannerherein described. This is particularly true when using either the liquidhydrocarbons or the gaseous hydrocarbons having. a high molecularweight.

It is indicated in the table above that the heat of formation and theheat absorbed by pyrolysis is different for the various hydrocarbons. Inmany instances pyrolytic reactions are endotherinic, and this seems tobe the case with many of the hydrocarbons or mixtures of hydrocarbonscommonly available in commercially large quantities at a low price. Now,when such a material is introduced into a mass of coking coal or theequivalent at a rate whereby heat is absorbed in reactions at a greaterrate than heat is transferred to the coking mass from the heating Wallsthe coking mass cools to an equilibrium point at which the amount ofdecompositionof the hydrocarbon is substantially that correspondingvtothe amount of heat input. 'I find that I can very appreciably increasethe output of gas, even without decreasing, in fact, even increasing thecoke-making capacity of the carbonizer by introducing into the cokingmass simultaneously with the hydrocarbon or with the hydrocarbon andsteam a combustion-supporting medium such asair, oxygen, oxygen-enrichedair or other reactant adapted to evolve heat by chemical. reaction. Inthis manner the heat of reaction may be supplied by combustion reactionswithin the Although I normally prefer to use that amount only ofoxidizing agent required to offset the cooling efiect of the endothermicreactions, it is beneficial and hastens the rate of carbonizing, tointroduce an excess of oxidizing agent during an early stage ofcarbonization, before maximum temperature in the mass of a solid fuel isreached, and a lesser amount at the the fuel mass, using the air in someexcess of the amount required to neutralize or offset the cooling effectof the pyrolysis of the hydrocarbon used; continue with this procedureadding steam also in a subsequent stage as found desirable, increasingthe amount of hydrocarbon in the late stage and post-carbonizing stageof processing, using steam alone for a brief period at the end of thecooling stage. lThe coke is preferably not completely cooled in thecarbonizer but merely cooled relative to maximum temperature at==tained.

This step of introducing an oxidizing agent into the fuel mass alongwith the hydrocarbon is of particular benefit when using an atomized oilas the hydrocarbon.- When using such a hydrocarbon more heat is requiredthan when using a gas because of the latent heat of vaporization of theoil. By the use ofa small amount of air, I. am able to use more oil, andobtain a greater quantity of liquid by-products including motor fuel,and gas.

There are certain mixtures of air and any particular hydrocarbon ormixture of hydrocarbons .that will not propagate flame at normaltemperature and at atmospheric pressure even though an igniting flame beapplied. In employing the oxidizing medium, usually air, in my process Ichoose to confine myself to these limiting mixtures. It is possible toemploy explosive mixtures if the velocity of injection is greater thanthe rate of flame propagation.

It will be noted that, using a refinery gas as the hydrocarbon, the heatof decomposition is very low because of the large percentage of ethyleneand propylene present and that accordingly only a very small relativeamount of oxygenneed be. used to mafntain a rate of heating of the massof solid fuel comparable with that in normal carbonization. It followsthat, unless a high output of coke or coke and gas are desired, onlysmall amounts of oxygen need be used with such a hydrocarbon.

When using air-hydrocarbon mixtures that border on the range where themixturewill propagate flame it is distinctly advantageous to use steamwith the hydrocarbon, the effect of the steam being to narrow the rangebetween the inflammable limits in amount of gas in the mixtures withair. When the hydrocarbon used is preheated, care should be used toavoid the .use of mixtures of air and hydrocarbon that will readilypropagate flame.

The word coke is used in the claims in the broad sense, and designatesthe solid fuel residue resulting from the carbonization by heating solidcarbonizable fuels to incandescence or to a carbonizing temperaturewhich, as stated, is commonly 1500 to l800 Fahrenheit.

Having described my invention so that one skilled in the art canpractice it, I claim:

1. A process for carbonizing solid fuels and making combustible gas,comprising, heating a confined mass of a carbonizable solid fuel to acarbonizing temperature liberating volatile mat ter from it as a gas andsimultaneously forming coke, introducing a substantially gaseouscombustible hydrocarbon into said mass during at least a part of theheating operation, at a rate sufiiciently slow for the pyrolyticformation therefrom of an additional amount of gas comprising hydrogen,withdrawing the gases as generated substantially free from entrainedcarbon resulting from pyrolysis of said hydrocarbon, and recovering thecoke separate from said gases.

2. A process for making coke and combustible gas substantially free fromsuspended carbon largely from a carbonizable solid fuel comprising,heating a confined mass of said solid fuel to a carbonizing temperatureliberating volatile matter from it as a gas and forming coke,introducing a gaseous hydrocarbon into said mass at a low ratesimultaneous with the application of heat thereto causing pyrolyis of atleast a portion of it thereby forming a gas containing hydrogensubstantially free from suspended carbon resulting from said pyrolysis,withdrawing the gases substantially as generated, and recovering thecoke separate from the gaseous products.

3. A process for making coke and combustible gas substantially free fromsuspended carbon from carbonizable solid fuel and a gaseous hydrocarbon,comprising, first heating a confined bed of said fuel to incandescencethereby evolving gas from said fuel, then continuing the heatingoperation and introducing into the heated,

bed a preheated gaseous hydrocarbon at a substantially definite rateforming an additional amount of gas comprising hydrogen, withdrawing thegases substantially as generated, and recovering the coke separate fromsaid gases, said rate being so low that the hydrogen gas as with: drawnfrom said bed is substantially free from entrained carbon blackresulting from the pyrolysis of said hydrocarbon.

4. In the process of making coke and combustible gas by carbonizing acarbonizable solid fuel and separately recovering said coke and gas, incombination the steps, passing through a confined heated bed of saidsolid fuel during the latter portion of the carbonizing period a gaseousstream initially consisting of a preheated gaseous hydrocarbon and steamat so slow a rate that said hydrocarbon reacts with said steam incontactwith the heated solid fuel in process while heat is being applied tosaid fuel, thereby produo ing coke and an additional amount ofcombustible gas which is substantially free from suspended carbonresulting from hydrocarbon pyrolysis, and separately recovering the cokeand combustible gas.

5. A process of making combustible gas and coke, comprising, heating aconfined mass of carbonizable solid fuel to incandescence therebyevolving combustible gas and carbonizing said solid fuel, introducing ata slow rate a mixture of a substantially gaseous hydrocarbon and a gascontaining free oxygen into the incandescent mass during the latter partof the heating period only, thereby forming an additional amount ofcombustible gas partly by exothermic reaction of oxygen with saidhydrocarbon and partly by pyrolysis of said hydrocarbon, depositing thefree carbon evolved by said pyrolysis on the surface of the heated solidfuel, removing and recovering the combustible gases substantially asformed and then separately recovering the coke.

6. In the process of making coke and combustible gas by carbonizing acarbonizable solid fuel and recovering coke separate from said gas, thestep comprising, introducing substantially together both a preheatedgaseous hydrocarbon and steam into a confined mass of said solid fuelwhile applying heat to said mass during a late stage of thecarbonization period at so slow a rate that they react chemically withone another by virtue of heat absorbed by them in said mass .therebyproducing coke and forming an additional amount of combustible gascontaining methane, hydrogen and carbonmonoxide that is substantiallyfree from entrained carbon black resulting from the pyrolysis of saidhydrocarbon; withdrawing the gases as generated, discontinuing thesteam-gas blast, and withdrawing and separately recovering said coke.

W W. ODELL.

